1. Field of the Invention
The present invention relates to electrical transducers. More specifically, the present invention is directed to a slide wire assembly.
2. Description of the Prior Art
A slide-wire assembly which function as a rheostat or voltage divider to vary an electrical resistance or to provide a variable output signal from a resistance element, i.e., slide-wire, contacted by a slide-wire brush or sliding contact have been used to provide electrical measurements of mechanical displacement, e.g., the slide-wire transducer shown in U.S. Pat. No. 2,866,877. Such measuring, or transducer, slide-wire elements have been actuated or driven by a measuring network which includes a motor drive for the slide-wire brush to rebalance the slide-wire while concurrently driving a recording pen for recording the reblance operation, e.g,, the measuring and recording system shown in U.S. Pat. No. 2,792,542. In order to provide accurate performance under widely varying adverse physical conditions there is a need for a slide-wire assembly which is capable of operating with precision under vigorous environmental conditions while still affording an economical structure capable of being produced by an assembly line manufacturing process at a low cost whereby a device such as a recorder incorporating such a slide-wire assembly may also have an ultimate low cost. The slide-wire assembly, therefore, must be compact and use a minimum number of parts, require a minimum of space while at the same time functioning with the required degree of precision that is normally encountered in typical slide-wire service. Such conditions include temperature variations, mechanical shocks, high frequency vibrations and other deleterious conditions. In order to attain the degree of precision required, the contact or brush which slides over a wire wound resistor of the slide-wire assembly must maintain continuous contact therewith a substantially uniform contact pressure to have a uniform and predictable variation in the output of the slide-wire assembly. Further, the assembly and adjustment of such a slide-wire assembly must be simple and require a minimum of parts in order to maintain the aforesaid low cost product characteristic. Additionally, inasmuch as the usual application for such a slide-wire assembly includes the need for a separately adjustable set-point potentiometer or rheostat, a greater saving in the product cost can be effected if the set-point slide-wire is incorporated in the same assembly with the aforesaid measuring slide-wire. Such a combined assembly must exhibit the same performance characteristics and manufacturing economies discussed above in order to produce a lost cost and acceptable ultimate product, e.g., a recorder.